📄 j-scwcd-12-2.html
字号:
bottomnextout.src="../i/next.gif";
topnextsectionout.src="../i/nextsection.gif";
topnextsectionover.src="../i/h-nextsection.gif";
bottomnextsectionout.src="../i/nextsection.gif";
bottomnextsectionover.src="../i/h-nextsection.gif";
}
function iOut(image)
{
if (browser=="N3")document[image].src=eval(image + "out.src");
}
function iOver(image)
{
if (browser=="N3")document[image].src=eval(image + "over.src");
}
// -->
</script><a href="#navskip"><img border="0" alt="Skip to main content" src="../i/c.gif"></a>
<table cellpadding="0" cellspacing="0" border="0" width="100%">
<tr>
<td class="tbgc" width="160"><a href="/developerWorks/cgi-bin/click.cgi?url=http://www.ibm.com/cn"><img height="47" width="160" alt="IBM" border="0" src="../i/ibm-logo.gif"></a></td><td class="tbg" width="195"><font color="#99ccff" size="2"><b>中国</b></font><a href="#main"><img alt="Skip to main content" height="1" width="195" border="0" src="../i/c.gif"></a></td><td valign="top" align="right" class="tbgc" width="100%">
<table cellspacing="0" cellpadding="0" border="0">
<form name="form1" id="form1" action="http://202.95.2.149/cgi-bin/dWsearch.pl" method="get">
<tr>
<td colspan="6"><img alt="" height="4" width="390" border="0" src="../i/c.gif"></td>
</tr>
<tr valign="middle">
<td class="dwsearch" height="8"><select class="dwsearch" name="selScope"><option value="dW">dW 中国所有内容</option><option value="dW">................. </option><option value="dW">dW 中国技术专区:</option><option value="comptZ"> 组件技术</option><option value="javaZ"> Java 技术</option><option value="linuxZ"> Linux</option><option value="xmlZ"> XML</option><option value="linuxZ">dW 中国特别专题:</option><option value="securityZ"> 安全</option><option value="unicodeZ"> Unicode</option><option value="all">IBM 全部内容</option></select></td><td class="small"><img alt="" border="0" height="1" width="5" src="../i/c.gif"></td><td><input maxlength="100" size="15" height="15" name="UserRestriction" class="dwsearch" type="text"></td><td><img alt="" height="1" width="5" border="0" src="../i/c.gif"></td><td width="64"><input alt="搜索" name="Search" value="Search" border="0" height="23" width="64" src="../i/search.gif" type="image"></td><td valign="top"><img alt="" height="1" width="34" border="0" src="../i/c.gif"></td>
</tr>
<tr valign="top">
<td class="small" colspan="6"><a target="_blank" style="color: #ffffff;" href="http://202.95.2.149/help.htm">高级搜索</a><img alt="" height="1" width="1" border="0" src="../i/c.gif"></td>
</tr>
<tr>
<td colspan="6"><img alt="" height="4" width="390" border="0" src="../i/c.gif"></td>
</tr>
</form>
</table>
</td>
</tr>
<tr>
<td class="hbg" height="21" width="160"></td><td class="bbg" valign="top" height="21" colspan="2"> <a href="/developerWorks/cgi-bin/click.cgi?url=http://www-900.ibm.com/cn/" class="mainlink">IBM 主页</a><span class="divider"> | </span><a href="/developerWorks/cgi-bin/click.cgi?url=http://www-900.ibm.com/cn/products/index.shtml" class="mainlink">产品与服务</a><span class="divider"> | </span><a href="/developerWorks/cgi-bin/click.cgi?url=http://www-900.ibm.com/cn/support/index.shtml" class="mainlink">支持与下载</a><span class="divider"> | </span><a href="/developerWorks/cgi-bin/click.cgi?url=http://www-900.ibm.com/cn/account/index.shtml" class="mainlink">个性化服务</a></td>
</tr>
</table>
<TABLE width="100%" cellspacing="0" cellpadding="0" border="0">
<TR>
<TD bgcolor="#ffffff" height="1" width="150"><IMG src="../i/c.gif" width="150" height="1"></TD>
</TR>
<TR>
<TD bgcolor="#cc6633" height="3" width="150"><IMG src="../i/c.gif" width="150" height="3"></TD>
</TR>
<TR>
<TD bgcolor="#333333" height="1" width="150"><IMG src="../i/c.gif" width="150" height="1"></TD>
</TR>
<TR>
<TD bgcolor="#000000" height="1" width="150"><IMG src="../i/c.gif" width="150" height="1"></TD>
</TR>
<TR>
<TD bgcolor="#ffffff" height="1" width="150"><IMG src="../i/c.gif" width="150" height="2"></TD>
</TR>
</TABLE>
<table border="0" cellpadding="0" cellspacing="0" width="100%">
<tr>
<td><font size="-1" face="Verdana, sans-serif"><a href="/developerWorks/cn/index.shtml">developerWorks 中国网站</a> : <a href="/developerWorks/cn/java/index.shtml">JAVA</a> ： <a href="/developerWorks/cn/cnedu.nsf/java-onlinecourse-bytitle?OpenView&Count=50">教学 - 在线教程</a></font>
<br>
<img alt="Java 认证成功之路，第 2 部分：SCWCD" src="imagemaster/masthead.jpg"></td><td width="*" valign="bottom" align="right"><a border="0" href="j-scwcd.zip"><img alt="下载 ZIP 文件" border="0" src="../i/icon-zip.gif"></a><a target="_blank" href="../tutorial_eng/index.html" border="0"><img alt="英文原文" border="0" src="../i/icon-source.gif"></a>
</td>
</tr>
<tr>
<td height="2" colspan="2"><img height="2" width="1" src="../i/c.gif"></td>
</tr>
</table>
<TABLE border="0" cellpadding="0" cellspacing="0" width="100%">
<TR>
<TD width="150" height="1" bgcolor="#000000" colspan="6"><IMG alt="" height="1" width="150" src="../i/c.gif"></TD>
</TR>
<TR>
<TD background="../i/sw-gold.gif"><a border="0" href="index.html" onMouseOver="iOver('topmain'); iOver('bottommain'); self.status=mainblurb; return true;" onMouseOut="iOut('topmain'); iOut('bottommain'); self.status=''; return true;"><img alt="主菜单" border="0" src="../i/main.gif" name="topmain"></a></TD><TD background="../i/sw-gold.gif"><a border="0" onMouseOver="iOver('topsection'); iOver('bottomsection'); self.status=sectionblurb; return true;" onMouseOut="iOut('topsection'); iOut('bottomsection'); self.status=''; return true;" href="index12.html"><img alt="章节菜单" border="0" src="../i/section.gif" name="topsection"></a></TD><TD background="../i/sw-gold.gif"><a border="0" onMouseOver="iOver('topfeedback'); iOver('bottomfeedback'); self.status=feedbackblurb; return true;" onMouseOut="iOut('topfeedback'); iOut('bottomfeedback'); self.status=''; return true;" href="j-scwcd-15-3.html"><img alt="给出此教程的反馈意见" border="0" src="../i/feedback.gif" name="topfeedback"></a></TD><TD width="100%" background="../i/sw-gold.gif"><img src="../i/c.gif"></TD><TD background="../i/sw-gold.gif"><a border="0" onMouseOver="iOver('topprevious'); iOver('bottomprevious'); self.status=previousblurb; return true;" onMouseOut="iOut('topprevious'); iOut('bottomprevious'); self.status=''; return true;" href="j-scwcd-12-1.html"><img alt="上页" border="0" src="../i/previous.gif" name="topprevious"></a></TD><TD background="../i/sw-gold.gif"><a border="0" onMouseOver="iOver('topnext'); iOver('bottomnext'); self.status=nextblurb; return true;" onMouseOut="iOut('topnext'); iOut('bottomnext'); self.status=''; return true;" href="j-scwcd-12-3.html"><img alt="下页" border="0" src="../i/next.gif" name="topnext"></a></TD>
</TR>
</TABLE>
<table bgcolor="ffffff" cellspacing="0" cellpadding="2" border="0" height="400" width="100%">
<tr valign="bottom">
<a name="navskip"></a><td height="25" colspan="4"><img alt="12.使用自定义标签开发 JSP 页面" src="imagemaster/titlebar12.jpg" border="0" height="25" width="562"></td>
</tr>
<tr>
<td bgcolor="ffffff" width="15"> </td><td bgcolor="ffffff" width="12"> </td><td valign="top" align="left" bgcolor="ffffff" width="*">
<p>
<br>
<table cellspacing="0" cellpadding="0" border="0">
<tr>
<td width="90%"><font size="4" face="Verdana, Arial, Helvetica"><b>标签库</b></font></td><td width="200" align="right"><font size="1" face="Verdana, Arial, Helvetica"><nobr> 第 2 页（共6 页）</nobr></font></td>
</tr>
</table>
<br>
<br>
</p>
<font size="2" face="Verdana, Arial, Helvetica">
<p>JSP 自定义标签是以标签库的形式分发的。标签库定义了一组相关的自定义标签，并包含了标签处理程序对象。这些处理程序对象是某些类的实例，这些类在 <code>javax.servlet.jsp.tagext</code> 包中实现了一些特殊的接口。当在页面中碰到自定义标签时，JSP 引挚会调用这些类的适当方法。</p>
<p>标签库必须先导入到 JSP 页面，然后才可以使用它的标签。</p>
<p>
<b>标签库指令</b>
<br>
在使用任何自定义标签前，标签库可以通过在页面中包含 <code>taglib</code> 指令来声明：</p>
<pre>
<code style="font-family: Courier New, Courier, monospace; font-size: 12">
<%@ taglib uri="/WEB-INF/mylib.tld" prefix="test" %>
</code>
</pre>
<p>
<code>uri</code> 属性指的是惟一标识标签库描述符（TLD）的 URI，它描述了与指定标签前缀有关的一组自定义标签。</p>
<p>自定义标签名称之前的前缀是由 prefix 属性指定的。您不能使用标签前缀 <code>jsp</code>、<code>jspx</code>、<code>java</code>、<code>javax</code>、<code>servlet</code>、<code>sun</code> 和 <code>sunw</code>，因为 Sun Microsystems 保留了这些。在 JSP 页面中可以使用多个 taglib 指令，每个当中定义的前缀必须是惟一的。</p>
<p>标签库描述符文件名必须具有扩展名 <code>.tld</code>，并存储在 WAR 的 WEB-INF 目录中，或者存储在 WEB-INF 的子目录中。</p>
<p>我们现在将讨论 <code>uri</code> 属性的可能值。<code>uri</code> 属性的值可以是 DTD 文件的绝对路径，如下所示：</p>
<ul>
<li>
<code><%@ taglib uri="/WEB-INF/mylib.tld" prefix="test" %></code>
</li>
</ul>
<p>可以指定逻辑名，该逻辑名将被映射到部署描述符中，TLD 文件的实际路径，如下所示：</p>
<ul>
<li>
<code><%@ taglib uri="/mylib" prefix="test" %></code>
</li>
</ul>
<p>部署描述符中的 <code><taglib></code> 元素可用于把逻辑名称映射到 TLD 文件的绝对路径。它具有两个元素：<code><taglib-uri></code> 指定了逻辑名称，<code><taglib-location></code> 给出了 TLD 文件路径。</p>
<p>例如，下面映射可用于把短名称 /mylib 映射到 /WEB-INF/mylib.tld。</p>
<pre>
<code style="font-family: Courier New, Courier, monospace; font-size: 12">
<taglib>
<taglib-uri>/mylib</taglib-uri>
<taglib-location> /WEB-INF/tld/mylib.tld </taglib-location>
</taglib>
</code>
</pre>
<p>即使没有在部署描述符中配置，也可以指定逻辑名称。容器读取 /WEB-INF/lib 目录中存在的打包 JAR 文件中的 TLD 文件。对于每个包含有关自己的 URI 的信息的 TLD 文件，JSP 引挚自动在指定 URI 和 TLD 文件的实际位置之间创建映射。</p>
<p>也可以把路径作为 <code>uri</code> 属性的值给予打包的 JAR 文件。在本例中，对于库中的所有标签，JAR 文件必须有标签处理程序。TLD 文件必须放在 JAR 文件的 META-INF 目录中。</p>
<pre>
<code style="font-family: Courier New, Courier, monospace; font-size: 12">
<%@ taglib uri="/WEB-INF/lib/mylib.jar" prefix="test" %>
</code>
</pre>
<p>实现标签处理程序的类可以以解包的形式，存储在 Web 应用程序的 WEB-INF/classes 子目录中。也可把它们打包到 JAR 文件，并存储在 Web 应用程序的 WEB-INF/lib 目录中。</p>
<br>
</font></td>
</tr>
</table>
<TABLE border="0" cellpadding="0" cellspacing="0" width="100%">
<TR>
<TD background="../i/sw-gold.gif"><a border="0" href="index.html" onMouseOver="iOver('topmain'); iOver('bottommain'); self.status=mainblurb; return true;" onMouseOut="iOut('topmain'); iOut('bottommain'); self.status=''; return true;"><img alt="主菜单" border="0" src="../i/main.gif" name="bottommain"></a></TD><TD background="../i/sw-gold.gif"><a border="0" onMouseOver="iOver('topsection'); iOver('bottomsection'); self.status=sectionblurb; return true;" onMouseOut="iOut('topsection'); iOut('bottomsection'); self.status=''; return true;" href="index12.html"><img alt="章节菜单" border="0" src="../i/section.gif" name="bottomsection"></a></TD><TD background="../i/sw-gold.gif"><a border="0" onMouseOver="iOver('topfeedback'); iOver('bottomfeedback'); self.status=feedbackblurb; return true;" onMouseOut="iOut('topfeedback'); iOut('bottomfeedback'); self.status=''; return true;" href="j-scwcd-15-3.html"><img alt="给出此教程的反馈意见" border="0" src="../i/feedback.gif" name="bottomfeedback"></a></TD><TD width="100%" background="../i/sw-gold.gif"><img src="../i/c.gif"></TD><TD background="../i/sw-gold.gif"><a border="0" onMouseOver="iOver('topprevious'); iOver('bottomprevious'); self.status=previousblurb; return true;" onMouseOut="iOut('topprevious'); iOut('bottomprevious'); self.status=''; return true;" href="j-scwcd-12-1.html"><img alt="上页" border="0" src="../i/previous.gif" name="bottomprevious"></a></TD><TD background="../i/sw-gold.gif"><a border="0" onMouseOver="iOver('topnext'); iOver('bottomnext'); self.status=nextblurb; return true;" onMouseOut="iOut('topnext'); iOut('bottomnext'); self.status=''; return true;" href="j-scwcd-12-3.html"><img alt="下页" border="0" src="../i/next.gif" name="bottomnext"></a></TD>
</TR>
<TR>
<TD width="150" height="1" bgcolor="#000000" colspan="6"><IMG alt="" height="1" width="150" src="../i/c.gif"></TD>
</TR>
</TABLE>
<TABLE width="100%" cellpadding="0" cellspacing="0" border="0">
<TR>
<TD width="100%">
<table border="0" cellpadding="0" cellspacing="0" width="100%">
<tr>
<td><img alt="" height="1" width="1" src="../i/c.gif"></td>
</tr>
<tr valign="top">
<td class="bbg" height="21"> <a class="mainlink" href="/developerWorks/cgi-bin/click.cgi?url=http://www-900.ibm.com/cn/ibm/index.shtml">关于 IBM</a><span class="divider"> | </span><a class="mainlink" href="/developerWorks/cgi-bin/click.cgi?url=http://www-900.ibm.com/cn/ibm/privacy/index.shtml">隐私条约</a><span class="divider"> | </span><a class="mainlink" href="/developerWorks/cgi-bin/click.cgi?url=http://www-900.ibm.com/cn/ibm/legal/index.shtml">法律条款</a><span class="divider"> | </span><a class="mainlink" href="/developerWorks/cgi-bin/click.cgi?url=http://www-900.ibm.com/cn/ibm/contact/index.shtml">联系 IBM</a></td>
</tr>
</table>
</TD>
</TR>
</TABLE>
<script src="//www.ibm.com/common/stats/stats.js" language="JavaScript1.2" type="text/javascript"></script>
<noscript>
<img border="0" alt="" height="1" width="1" src="//stats.www.ibm.com/rc/images/uc.GIF?R=noscript"></noscript>
</body>
</html>
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -